1. Field of the Invention
The invention relates to a screw having a screw head, a screw shank and a corrugated conical flange which decreases in thickness towards its periphery and will abut on a component part as the screw is being screwed into the latter.
2. Description of Background Art
A screw of this kind is illustrated and described in European patent specification 00 28 746 A1. As shown in FIG. 11 of this printed document, the screw described therein having a screw head and a screw shank also includes a flange which will contact the surface of a component part as the screw is being screwed into the latter and will be deformed in this process. The sectional view of FIG. 11 shows the screw in its non-tightened state. This flange has a planar lateral surface facing the component part which bends slightly toward the component part approximately in the middle of the flange so as to form an indentation. As a result, the flange tapers to a certain extent and decreases in thickness from the indentation toward its periphery. As the screw is being screwed into the component part, the outer periphery of the flange will first contact the component part and then be bent back about the indentation until the planar surface of the flange contacts the component part. This will provide feedback to the user that the minimum preload force required for this purpose has been reached. Furthermore, the section of the flange extending from its indentation to its periphery is corrugated, which corrugation will to a certain extent absorb the impact of the flange impinging on the component part. The margin for this cushioning effect by the corrugation is kept rather small since the flange also has a planar surface which extends over its inner half. As a result, this inner planar portion of the flange will contact the component part very shortly after the periphery of the flange has contacted the component part, thus practically preventing any further screwing of the screw into the component part.